The indirect injection diesel engine has now given way in the market place almost entirely to more modern direct injection light duty diesel engines for reasons of fuel economy, performance, and low emissions. However, direct injection diesel engines are much more sophisticated than the earlier indirect injection engines and require more precise calibration be maintained in order to maintain their design performance. The injectors, key components in the performance of the engine, are vulnerable to having their operation perturbed by fouling from deposits resulting from injection or combustion of fuel.
Direct injection engines may also use a high pressure common rail fuel system or a unity injection system. Recent problems have arisen with the use of low sulfur and ultra low sulfur diesel fuels when used in such high pressure common rail fuel systems. By “high pressure” herein is meant those pressures in diesel fuel systems that are equal to or greater than 15,000 psi (greater than or equal to 1000 bar). Such problems are evident by occurrence of sediment in the fuel additive packages, internal injector deposits, and injector sticking Accordingly, there was a need to provide fuel additives that are effective to reduce the amount of deposits in the fuel systems and/or effective to clean up fouled fuel systems.
In view of the foregoing and other needs, embodiments of the disclosure provide a diesel fuel additive composition, a fuel containing the fuel additive, a method for improving diesel engine performance using the additive. The diesel fuel additive includes a reaction product of (a) a hydrocarbyl-substituted acylating agent and (b) a reactant selected from the group consisting of a nitrogen-containing compound, a hydroxyl-containing compound, and water that provides a reaction product selected from the group consisting (1) a mono-amide/mono-acid or metal free mono-acid salt thereof, (2) a diacid or metal free diacid salt thereof, and (3) mono-ester/mono-acid or metal free mono-acid salt thereof, wherein the reaction product includes at least about 10 molar percent of acid groups based on total moles of the reaction product.
In another embodiment of the present disclosure provides a method for improving the performance of an engine combusting a diesel fuel having less than 50 ppm by weight or less sulfur, typically less than about 20 ppm sulfur by weight based on a total weight of the fuel. The method includes combining a low sulfur middle distillate fuel with a fuel additive comprising a reaction product of (a) a hydrocarbyl-substituted acylating agent and (b) a reactant selected from the group consisting of a nitrogen-containing compound, a hydroxyl-containing compound, and water that provides a reaction product selected from the group consisting (1) a mono-amide/mono-acid or metal free mono-acid salt thereof, (2) a diacid or metal free diacid salt thereof, and (3) mono-ester/mono-acid or metal free mono-acid salt thereof, wherein the reaction product includes at least about 10 molar percent acid groups based on total moles of the reaction product. The additized fuel is combusted in the engine, whereby the performance of the engine is improved relative to the performance of the engine in the absence of the fuel additive.
Yet another embodiment of the disclosure provides a low sulfur diesel fuel composition suitable for a high pressure compression ignition engine. The diesel fuel composition includes a) a major amount of low sulfur diesel fuel, and b) a minor amount of additive for reducing injector and fuel system deposits. The additive is a reaction product of (i) a hydrocarbyl-substituted acylating agent and (ii) a reactant selected from the group consisting of a nitrogen-containing compound, a hydroxyl-containing compound, and water that provides a reaction product selected from the group consisting (1) a mono-amide/mono-acid or metal free mono-acid salt thereof, (2) a diacid or metal free diacid salt thereof, and (3) mono-ester/mono-acid or metal free mono-acid salt thereof, wherein the reaction product includes at least about 10 molar percent acid groups based on total moles of the reaction product.
Other embodiments of the disclosure provide a method for increasing fuel economy of a vehicle, comprising combusting the diesel fuel composition as described herein wherein said fuel economy increase is defined by power recovery, and said power recovery is greater than 50% as determined by the formulaPower recovery=(DU−CU)/DUwherein DU is a percent power loss during a dirty-up phase without the additive, CU is the percent power loss during a clean-up phase with the fuel additive, and power is measured according to CEC F98-08 DW10 test.
According to one or more embodiments of the disclosure, the additive for use in diesel fuel may provide benefits that include, but are not limited to: a) maintaining clean fuel delivery systems including injectors and fuel filters; b) an ability to clean-up dirty or fouled fuel delivery systems; c) a contribution to boosting or increasing fuel economy; d) reducing combustion system deposits; e) reducing fuel system corrosion; f) and improving lubrication of the fuel system and combustion chamber. The additives of the disclosure may provide similar benefits to other middle distillate fuels, such as home heating oils, marine fuel, and jet fuel.